1. Field of the Invention
The present invention relates in general to valve trains of overhead camshaft engines and of the kind wherein a rocker is incorporated to transfer motion from a cam to a valve stem, and more particularly to means for taking up the play or slack in the valve trains.
2. Description of the Prior Art
Such valve trains as described above are known as a rocker-arm type and a swing-arm type. FIG. 1 shows a prior art rocker-arm type valve train which comprises a cam 10 rotatable together with an overhead camshaft 12, a poppet valve 14 having a valve stem 14a and a rocker arm 16 rotatable on a rocker shaft 18 and having a first end portion 16a in contact with the cam 10 and a second end portion 16b in contact with the end of the valve stem 14a such that the rocker arm 16 will transfer motion from the cam 10 to the valve stem 14a. A valve clearance adjuster generally indicated at 20 is provided for adjustment of clearance or slack C in the valve train. The valve clearance adjuster 20 is mounted on the second end portion 16b of the rocker arm 16 and consists of an adjusting screw 20a and a lock nut 20b.
As is well known in the art, the valve train requires enough slack C to make sure that when the engine is extremely hot the expansion of parts will not result in holding the valve 14 off of its seat. As a consequence, when the engine is cold or moderately hot, the valve train is noisy.